Headphones for reproducing four-channel sound

ABSTRACT

Each headphone casing encloses forwardly and rearwardly extending, segregated, acoustic mixing chambers segregated by a generally vertical partition and opening inwardly through a common, generally central opening to an ear of the person wearing the headphones. The headphone segregated mixing chambers preferably have specifically contoured walls with a sound emitting device in each mixing chamber directed at least partially against said walls for a proper sound mixing in each mixing chamber and the headphones central openings are of appropriate various sizes and depth for at least fully receiving the persons ear with acoustic integrating chambers of various sizes formed by the central openings adjacent the ears and simultaneously communicating with each of the segregated mixing chambers. Thus, with one channel of four-channel sound directed into each of the mixing chambers of a set of the earphones, the full effect of four-channel sound is received, and by similar connection of stereophonic sound, many of the four-channel sound effects are reproduced from the stereophonic sound.

United States Patent [191 Greuzerd et al. v

[4 1 Feb. 26, 1974 HEADPHONES FOR REPRODUCING FOUR-CHANNEL SOUND [75]inventors: Charles E. Greuzerd, Garden Grove; Louis Lawrence l-lenkin,Huntington Park, both of Calif.

[73] Assignees: Victor B. Morgan, Los Alamitos;

Thomas P. Mahoney; George E. Schick, both of Santa Monica, all of,Calif. part interest to each [22] Filed: Aug. 23, 1971 [21] App]. No.:173,809

[52] US. Cl. 179/156 R, 179/] GO, 179/182 R [51] Int. Cl. H04m 1/05 [58]Field of Search....'.. 179/1 G, 1 GA, 156 R, 182

Fixler 179/1 G Primary Examiner-William C. Cooper Atto'rney, Agent, orFirm-Mahoney, Schick &'Cislo 57 ABSTRACT Each headphone casing enclosesforwardly and rearwardly extending, segregated, acoustic mixing chamberssegregated by a generally vertical partition and opening inwardlythrough a common, generally central opening to an ear of the personwearing the headphones. The headphone segregated mixing chamberspreferably have specifically contoured walls with a sound emittingdevice in each mixing chamber directed at least partially against saidwalls for a proper sound mixing in each mixing chamber and the headphones central openings are of appropriate various sizes and depth forat least fully receiving the persons ear with acoustic integratingchambers of various sizes formed by the central openings adjacent theears and simultaneously communicating with each of the segregated mixingchambers. Thus, with one channel of four-channel sound directed intoeach of the mixing chambers of a set of the earphones, the full effectof four-channel sound is received, and by similar connection ofstereophonic sound,.many of the four-channel sound effects arereproduced from the stereophonic sound.

15 Claims, 9 Drawing Figures PATENTEDFEBZB 1974 INVEVNTORS. CHARLES E.GREUZARD By Laws L. HENKIN MAHONEY, HORNBAKER AND SCH/CK ATTORNEYSPATENTEDFEBZG I974 SHEET 2 BF 4 IN VENTORS.

CHARLES E. GREuzARo BY Lou/s L. HENKIN HONEY, HORNBA KER AND SCH/CKATTORNEYS PAIENTEflraszs I974 3.794379 sumanra INVENTO CHARLES E. GREUZAY Lou/s L. HENKIN MA HONEY, HORNBA KER AND SCH/CK ATTORNEYS PATENIEDFB26i974 3,7 94,7 7 9 SHEET '4 0r 4 INVENTORS. CHARLES E. GREUZARD BY LOU/5'L. HENK/N I MAHONE Y, HORNBAKER AND SCHICK ATY ORNEYS HEADPHONES FORREPRODUCING FOUR-CHANNEL SOUND BACKGROUND OF THE INVENTION Thisinvention relates to specifically formed headphones adapted forreproducing four-channel sound, and more particularly, to uniqueheadphones, each having forward and rearward, segregated, mixingchambers, each capable of receiving a different single channel offour-channel sound for effectively reproducing such four-channel soundwith a similar effect to four-channel remote speakers. The result isthat with the headphones of the present invention, a personalization offour-channal sound is obtained, the same function of earphones as hasbeen previously done with monaural and stereophonic sounds, yet the fulleffects of four-channel sound remain uninhibited just as if four-channelsound remote speakers were being used.

In the reproduction of monaural or single channel sound, merely a singlesound emitting device is required and this is true whether or not thesingle sound emitting device may be made up of a group of speakers, eachadapted for more perfectly reproducing single tone ranges of the singlechannel sound. Adapting the monaural or single channel sound to thepersonalization of headphones was obviously a relatively simple matter,there being one sound emitting device for each of the ears of the personwearing the headphones and again, whether or not each of these soundemitting devices included a series of sound emitters, each adapted for aparticular tone range of the overall sound being received. The importantpoint is that whether by a remote sound emitting device, such as aspeaker device, or whether by a single or set of headphones for thepersonalization, it was readily distinguishable by the person listeningto such sound that it was being received from a single source.

With the advent of stereophonic sound in the form of two-channel sound,for proper reproduction thereof, it was necessary to provide two spaced,remote, sound emitting devices or speakers, the best results being whenthe person listening to the sound is positioned between the speakers.Thus, the adaption of two-channel sound to the personalization ofearphones was still a relatively simple matter, it merely beingnecessary to provide earphones, each having a separate sound emittingdevice therein and each of the separate sound emitting devices beingconnected to the separate two sound channels. In this manner,two-channel sound could be and is effectively reproduced both withremote speakers systems or personalized headphones, in either case theperson listening to the same having some effect of sitting within thereproduced sound.

With the introduction of four-channel sound, however, completelydifferent problems are presented in adapting the reproduction of thesame from the remote speaker systems to the personalized headphonesystem. With four-channel sound, it is not merely the effect of beingpositioned between sound emitting devices so as to be partiallyenveloped by the sound from direct opposite sides as in two-channelsound, but it is the effect of being completely enveloped by sound withthe ears of the person receiving such sound detecting sounds coming fromthe rearward directions and the forward directions, and from both sides.The complexity of the problems involved can be even more clearlyappreciated when it is considered that with monaural or single channelsound and stereophonic in the form of twochannel sound, there is noforward and rearward directional sound effect and it is merely necessaryto position the sound emitting devices adjacent each of the ears anddirect the sound into the ears.

In four-channel sound, however, the reproduction of the four directionsound and the recognition thereof by the ears must be on a directionallbasis, one sound emitting device at either side from forward and thesame from rearwardJFurthermore, none of the sound emitting devices infour channel sound reproduction can be directed specifically at the earfor the reason that it would be impossible for the ear to truly detectthe direction thereof when the ear is merely receiving sounds from soundemitting devices merely slightly forwardly and rearwardly of each other.

In the reproduction of four-channel sound with speakers systems, it ispossible to authentically reproduce the four-channel sound merely by theremote placements of the various channel receiving speakers. In otherwords, if the person listening to the fourchannel sound is positionedsurrounded by the individual channel speaker systems, it is readilyrecognized by the ears that one channel is being received generally fromeach of the forward sides and one channel is being received from each ofthe rearward sides, again due to the remoteness of the speaker systems.Using the simple concepts of the prior headphone constructions, however,the effect of attempting to personalize fourchannel sound to headphonereproduction is to move each of the remote speakers or sound emittingdevices into relatively close forward and rearward proximity, necessaryfor the relatively small headphone units and this as hereinbeforepointed out, makes it virtually impossible with the prior headphoneconcepts for the ears to detect the forward and rearward directionalreception of the sounds, thereby completely destroying the four-channelsound effect.

OBJECTS AND SUMMARY OF THE INVENTION It is, therefore, an object of thisinvention to provide headphones adapted for reproducing four-channelsound wherein a reasonable reproduction of fourchannel sound isobtained, while still maintaining the headphones of a reasonable andusable size. According to broader concepts of the presentinvention, eachof the earphones is provided with forward and rearward mixing chambers,each having a sound emitting device therein and with the mixing chambersbeing separated in each headphone by a generally vertical partition. Thesound emitting devices in the respective mixing chambers are directed atleast partially against chamber walls, rather than directly at thecentral opening inwardly communicating with the ear of the personwearing the headphones. Thus, the sounds produced in the various mixingchambers give directional reproduction readily detected by the ear andreproducing the forward and rearward directional transmission foraccomplishing the reproduction of the four-channel sound.

It is a further object of this invention to provide headphones adaptedfor reproducing four-channel sound involving the foregoing broadconcepts wherein fourchannel sound reproductions of maximum quality areproduced by specific contouring of the mixing chamber wall and thedirection of sound from the sound transmitting devices at specificlocations on said wall. For

maximum quality and authenticity of four-channel sound reproduction,each of the forward and rearward mixing chambers of each of theheadphones is preferably generaly ovoidal in horizontal cross-sectionsand preferably generally elipsoidal in vertical cross-sections in theextensions thereof within the headphone casings from the casing innersides, the horizontal crosssectional ovoidal shapes having their maximumoutsound reproduction.

It is still a further object of this invention to provide headphonesadapted for reproducing four-channel sound wherein even increasedauthenticity of sound reproduction may be produced with a commonintegrating chamber communicating with the respective forward andrearward mixing chambers of each of the earphones. Each of the earphonesis provided with a generally central opening communicating with each ofthe mixing chambers for positioning at the ear of the person receivingthe sound, such central opening preferably being of appropriate size atleast for fully receiving the ear therein and with the depth of thecentral opening or the outward dimensions thereof to the mixing chambersbeing sufficient for providing the integrating chamber adjacent the earand extending forwardly and rearwardly various amounts for variousoutward communications with the mixing chambers. Thus, each of themixing chambers communicates to the headphone central opening at eitherside of the vertical partition and into the integrating chamber fortransmission from such integrating chamber to the ear, even morecompletely reproducing the four-channel sound and giving the effect ofsound emitting devices a far greater distance from the ear than is theactual case.

It is an additional object of this invention to provide headphonesadapted for reproducing four-channel sound of the foregoing generalcharacter which, by simple switch means, may be adapted compatible withvirtually any form four-channel sound system, as well as providingcertain of the four-channel sound effects from two-channel soundsystems. The various sound emitting devices of the headphones areconnected to the respective sound producing devices through amulti-positionable switch which may be adjusted for transmitting thesound of any given sound transmission device to any given sound emittingdevice in any of the four mixing chambers of the headphone set. In thismanner, all possible combinations of sound transmission to individualheadphone mixing chambers may be obtained without a separate, specificwiring being required for each individual case, including that wheresterophonic or two-channel sound is to be used.

Other objects and advantages of the invention will be apparent from thefollowing specification and the accompanying drawing which are for thepurpose of illustration only.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary, frontelevational view illustrating an embodiment of the headphones of thepresent invention in proper position covering the ears of a personwearing a set of such headphones;

FIG. 2 is an enalarged, fragmentary, horizontal sectional view, lookingin the direction of the arrows 2-2 in FIG. 1, and showing the embodimentof the headphones of the present invention oppositely connected to amulti-positionable switch and further illustrating the relativepositioning of theears within central openings of the headphones of theperson wearing the headphones;

FIG. 3 is a fragmentary, vertical perspective sectional view, looking inthe direction of the arrows 3-3 in FIG. 2, more clearly showing theinternal construction of one of the headphones of FIG. 2, an approximatequarter section being taken from a forward mixing chamber portion of theheadphone to even further illustrate the internal construction of theheadphone mixing chambers;

FIG. 4 is a diagramatic top plan view of an orchestra with soundproducing devices positioned therearound and to which the sound emittingdevices of the head phones might be connected for illustrating one useof the headphones of the present invention;

FIG. 5 is a horizontal sectional view similar to the view of FIG. 2, butonly of a single headphone, illustrating a second embodiment of theheadphones of the present invention;

FIG. 6 is a vertical perspective sectional view, looking in thedirection of the arrows 66 in FIG. 5, and similar to FIG. 3;

FIG. 7 is a vertical sectional view, looking in the direction of thearrows 77 in FIG. 6;

FIG. 8 is a horizontal sectional view similar to the view of FIG. 5,illustrating a third embodiment of the headphones of the presentinvention; and

FIG. 9 is a vertical sectional view, looking in the direction of thearrows 99 in FIG. 8.

Description of the'Best Embodiments Contemplated:

Referring to FIGS. 1 to 3 of the drawings, an embodiment of theheadphones incorporating the principles of the present invention isillustrated, the two headphones of a set being virtually identical withthe usual opposite positioning over the two ears of a person using thesame. As shown, each headphone includes a main hollow casing gnerallyindicated at 10 segregated into outward, somewhat bulbous, forward andrearward acoustic mixing chambers generally indicated at 12 and 14,respectively. The segregation of the casing 10 to separate the mixingchambers 12 and 14 is preferably accomplished by a generally forwardlyand rearwardly central and generally vertically extending partition 16which terminates inwardly at an outer portion of an preferably forwardlyand rearwardly generally centrally segregating a generally central earopening 18, the ear opening, in this case being concentrated centrally.

The ear opening 18, for maximum results, is of outward depth ordimensions from a generally flat casing inner side 20 at leastsufficient to fully receive an ear 22 of a person wearing the particularheadphone while still maintaining the partition 16 spaced outwardlytherefrom, thereby providing an acoustic integrating chamber 24outwardly of the ear 22 and inwardly of the inner termination of thepartition 16. The ear opening 18 and, therefore, the integrating chamber24, extends forwardly and outwardly into communication with the forwardmixing chamber 12 forwardly adjacent the partition l6, and rearwardlyand outwardly into communication with the rearward mixing chamber 14rearwardly adjacent the partition 16. The relationship between theoutward depth of the ear opening 18, the size of such ear openingrelative to the ear 22 and the outward positioning of the partition 16is illustrated in FIG. 2, it being seen that the integrating chamber 24extends forwardly and rearwardly between the communication thereof withthe forward and rearward mixing chambers 12 and 14 as well ascommunicating with the ear 22, the depth of the opening being formed bythe outward thicknesses of a usual resilient material head pad 26 and aninner wall 28 of the main portion of the casing 10. Obviously, ifdesired, the inner wall 28 may actually connect to the inner end of thepartition 16 with appropriate perforations therethrough into the centralear opening 18.

As further shown in FIG. 2, the head pad 26 and the casing inner wall 28close the forward and rearward mixing chambers 12 and 14 except for theopening thereof, into the integrating chamber 24, whether adjacent thepartition 16, or otherwise, the walls of the mixing chambers outwardlyof the casing inner side 20 or the casing inner wall 28 preferably beingspecifically arcuate, including the walls formed by the partition 16. Asmay be seen in both FIGS. 2 and 3, each of the forward and rearwardmixing chambers 12 and 14 are preferably of generally ovoidal horizontalcrosssections gradually diminishing to the upward and downwardextremities thereof and having maximum outward and depth dimensions fromthe casing inner side 20 toward the partition 16, that is, at locationslesser horizontal distances from the casing partition than thehorizontal midpoint distances of the mixing chambers. Furthermore, theforward and rearward mixing chambers 12 and 14 are preferably elipsoidalin vertical cross-sections outwardly from the casing inner side 20,again diminishing toward the forward and rearward extremities thereof. 1

A sound emitting device 30, such as the usual miniature earphonespeakers, is positioned in each ofthe forward and rearward mixingchambers 12 and 14, the forward mixing chamber device 30 being in theforward extremity thereof and the rearward mixing chamber device 30being in the rearward extremity thereof. The separate sound emittingdevices 30 may be of any usual form including single overall tone rangespeakers or a I series of different tone range speakers to cover theentire tone range as is usual practice and well known to those skilledin the art. More important, the sound emitting devices 30 are positionedwithin the forward and rearward mixing chambers 12 and 14 so as to notprincipally direct the sound therefrom directly toward the ear opening18 and the integrating chamber 24, but rather to direct the soundtherefrom principally toward inner wall surfaces 32 of the mixingchamber, for best results, preferably principally toward the arcuateinner wall surfaces formed by the partition 16 in each of these mixingchambers.

For expediency of manufacturing, the main portions of the casing may beof the usual molded plastics in the specific shapes described. Also, thehead pad 26 may be of the usual sponge or foamed plastics to provide theusual resilient qualities thereof. The sound emitting devices 30, ashereinbefore described, may be of usual construction merely properlycontoured for mounting in the forward and rearward mixing chambers 12and 14 as described.

Each of the sound emitting devices 30 is separately wired preferablythrough a multi-positionable switch 34, and from such switch, toindividual sound producing devices 36 shown diagramatically in FIG. 4.Referring simultaneously to FIGS. 2 and 4 for illustration of a use ofthe headphones of the present invention, FIG. 4 illustratesdiagramatically an orchestra 38 denoted by the orchestra leader asfacing the bottom of the sheet of the drawing, the sound producingdevices 36 being equally spaced around the orchestra and, in this case,being sound pick-up devices. Continuing the example and considering theusual arrangement of four-channel sound reception, the lowest or forwardsound producing device 36 of FIG. 4 would be connected to the soundemitting device 30 of the left earphone forward mixing chamber 12 ofFIG. 2, the left rear sound producing device 36 of FIG. 4 to the soundemitting device 30 of the left headphone rearward mixing chamber 14, theright forward sound producing device 36 of FIG. 4 to the sound emittingdevice 30 of the right headphone forward mixing chamber, and the rightrearward sound producing device 36 of FIG. 4 to the sound emitting device 30 of the right headphone rearward mixing chamber 14.

Thus, the effect to the person wearing the headphones would be that ofbeing positioned centrally of the orchestra and facing forwardly in thesame direction of the orchestra. If the effect were desired of being inthe position of a person in the audience at the front of the orchestra,the connections to the forward and rearward mixing chambers 12 and 14 ofan individual earphone of FIG. 2 would be directly reversed and this isone of the purposes of the multi-positionable switch 34 to accomplishthis merely by changing the position of the switch. Also, it is obviousthat although the illustration of FIG. 4 is a live orchestra 38, afour-channel tape of a similar recording of the orchestra would produceprecisely the same effect, the particular sound producing devices 36being the sound pick-ups of the tape connected to the various of thesound emitting devices 30 in the headphone mixing chambers 12 and 14.

The foregoing has given two possible connections of the headphones ofthe present invention through the v multi-positionable switch 34 andvarious other positions of the switch would be other possible combinations varied from that set forth. Various present day four-channel soundsystems have various theories as to the manner of connecting aparticular of the mixing chambers 12 or 14 to the particular of thesound producing devices 36 or the equivalent tape channel pickups andthe switch can be arranged in a manner well known to those skilled inthe art so as to provide for each of these various possible connectionsmerely by a repositioning of the switch. Still in addition, certain ofthe effects of four-channel sound can be reproduced from two-channelsound tapes or sound producing devices 36 and the switch 34 may haveadditional positions for accommodating the various possible connectionsinto the earphones of the present invention of such two-channel sound,again, all obvious to those skilled in the art.

Regardless of the particular line of connections between the soundproducing devices 36 or their equivalent and the sound emitting devices30 of the various mixing chambers 12 and 14, with the particularconstruction of headphones described, each sound emitting device 30 willreproduce its particular sound and direct the same toward the arcuatesurfaces of the particular mixing chamber 12 or 14 principally towardthe particular partition 16 and with the specific contouring of themixing chamber as hereinbefore described, such sound will deflect fromthe arcuate walls and be mixed giving it both the quality of depth anddirection followed by integration with the other mixing chamber of thatparticular headphone as the sound leaves the mixing chamber and entersthe integrating chamber 24 of the particular ear opening 18, finallybeing received by the ear 22. The overall effect is that the human car22 will be given the illusion of sound depth approaching that ofactually being present at and listening to the sound producing media,whether the orchestra 38 or otherwise. At the same time, the human ear22 will detect separated direction of reception, from generally forwardas a result of the forward mixing chambers 12 and from generallyrearward as a result of the rearward mixing chambers 14, all of whichwill give a maximum quality of four-channel sound reproduction.

Referring to FIGS. through 7, a second embodiment of the headphones ofthe present invention is illustrated therein, the headphones shown beingidentical to those of FIGS. 1 through 3 with the sole exception of theaddition of similar arcuate protrusions 40, one each protruding intoeach of the mixing chambers 12 and 14 principally from the inner wallsurfaces 32 at opposite sides of the partition 16 and covering the majorportion of such partition inner wall surfaces. As shown particularly inFIGS. 6 and 7, the protrusions 40 are preferably elipsoidal in verticalcross-sections diminishing smoothly inwardly and outwardly of the easinginner side 20 and terminating inwardly spaced outwardly of the innertermination of the partition 16. It is felt that, at least with certaintypes of sound and certain types of sound reproduction that theprotrusions 40 will increase the quality of mixing within the particularmixing chamber 12 or 14 from the particular sound emitting device togive increased qualities of sound reproduction to the ear 22.

Referring to FIGS. 8 and 9, a third embodiment of the headphones of thepresent invention is illustrated therein, again, the headphones shownbeing identical to those of FIGS. 1 through 3 with the exception of adifferent overall extension of the casing inner wall 28, a lesser sizedformation of the head pad 26 so as to produce a far more extensive earopening 18 and integrating chamber 24, and a different communicationbetween the mixing chambers 12 and 14 and the ear central opening 18 andintegrating chamber 24. As shown, the casing inner wall 28 is preferablysolid in an area encompassing the inner termination of the partition 16,such area extending both forwardly and rearwardly over a partial inwardtermination of the mixing chambers. This solid area of'the casing innerwall 28 is preferably circular in extremity contour and forwardly,rearwardly, above and below this solid area, the casing inner wall isformed with a multiplicity of perforations 42 therethrough communicatingupwardly into each of the mixing chambers 12 and 14.

The head pad 26 is of greatly reduced cross-sectional dimensions andcircumscribes the casing inner wall 28 only at the extremities thereofin all directions beyond the location of the perforations 42. The resultis that the now reduced head pad 26 in the positioning thereof againstthe head of a person wearing the headphones seals off a much moreextensive ear central opening 18, although the ear is still preferablypositioned centrally thereof at the partition 16 and inwardly of thesolid area of the casing inner wall 28. The integrating chamber 24,however, is greatly forwardly, rearwardly, upwardly and downwardlyenlarged, but still communicating from the mixing chambers 12 and 14through the perforations 42 into the integrating chamber at theextremities thereof, the integrating chamber extending fully between themixing chambers 12 and 14 and fully in communication with the ear 22.

This third embodiment of the headphones of the present invention in viewof the increased size of the ear central opening 18 and the integratingchamber 24, will even further increase the separation of sound from eachof the individual mixing chambers 12 and 14 in order to permit the earto receive the effect of spaced forwardly and rearwardly soundreproduction. In this manner, a more perfect fourchannel soundreproduction is produced while still maintaining such reproduction inpersonalized headphones. Furthermore, this increased sound separationeffect of the increased integrating chamber 24 will cooperate with themixed sound of the mixing chambers 12 and 14, whether these mixingchambers and the partition 16 are of the form shown in FIGS. 1 through 3of FIGS. 5 through 7.

Thus, according to the principles of the present invention, headphonesare provided for quality reproduction of four-channel sound, such resultnot being heretofore possible with the prior headphones construction.Furthermore, according to certain of the principles of the presentinvention, by connection of the unique headphones through amulti-positionable switch, it is possible to adapt the same to virtuallyany form or therory of four-channel sound merely by a repositioning ofthe switch. Still in addition, with the use of the head phones of thepresent invention and preferably again through the muIti-positionableswitch, it is possible to make use of two-channel sound and give thesame certain of the effects of four-channel sound.

We claim:

I. In a headphone construction, the combination of: a main generallyhollow casing having a generally central opening at an inner sidepositionable at an ear of a person, said casing enclosing forwardly andrearwardly extending segregated acoustic mixing chambers separated by aportion of said casing and each opening through said casing centralopening; and a sound emitting device in each of said mixing chamberspositioned directing sound into the respective of said mixing chambers,said sound emitting devices in each of said mixing chambers beingprincipally directed toward walls of said respective mixing chambersformed by said portion of said casing separating said mixing chambers.

2. The headphone construction as defined in claim 1 in which said casingcentral opening forming an acoustic integrating chamber between saidmixing chambers and said ear inwardly of said portion of said casingseparating said mixing chambers.

3. The headphone construction as defined in claim 1 in which each ofsaid mixing chambers in extension thereof outwardly and forwardly andrearwardly from said casing inner side is generally ovoidal inhorizontal cross section and generally ellipsoidal in vertical crosssection.

4. In a headphone construction, the combination of: a main casing havinga generally vertical partition separating said easing into forward andrearward acoustic mixing chambers, said casing being adapted forpositioning with a casing inner side against the head of a personcovering an ear and with said partition at said ear, said casing andsaid partition forming walls defining said chambers; said forward mixingchamber opening through said casing forwardly of said partition to saidear; said rearward mixing chamber opening through said casing rearwardlyof said partition to said ear; and asound emitting device in each ofsaid mixing chambers directing sound into the respective one of saidmixing chambers, said sound emitting devices in each of said mixingchambers being principally directed toward walls of said respectivechambers formed by said partition.

5. The headphone construction as defined in claim 4 in which said soundemitting device in said forward mixing chamber is at a forward extremityof said forward mixing chamber directed rearwardly; and in which saidsound emitting device in said rearward mixing chamber is at a rearwardextremity of said rearward mixing chamber directed forwardly.

6. The headphone construction as defined in claim 4 in which saidforward and rearward mixing chambers communicate through said casinginner side through an acoustic integrating chamber in said casinginwardly of an inner termination of said partition.

7. The headphone construction as defined in claim 4 in which said wallsof said forward and rearward mixing chambers outwardly of said casinginner side including said partition are arcuate in horizontal crosssection.

8. The headphone construction as defined in claim 4 in which said wallsof said forward and rearward mixing chambers outwardly of said casinginner side including said partition are arcuate in vertical crosssection.

9. The headphone construction as defined in claim 4 in which said wallsof said forward and rearward mixing chambers outwardly of said casinginner side including said partition are arcuate in both vertical andhorizontal cross section.

10. The headphone construction as defined in claim 4 in which said wallsof said forward and rearward mixing chambers outwardly of said casinginner side including said partition are generally ellipsoidal invertical cross section.

11. The headphone construction as defined in claim 4 in which said wallsof said forward and rearward mixing chambers outwardly of said casinginner side including said partition are generally ovoidal in horizontalcross section.

12. The headphone construction as defined in claim 4 in which said wallsof said forward and rearward mixing chambers outwardly of said casinginner side including said partition are generally ellipsoidal invertical cross section and generally ovoidal in horizontal crosssection, said mixing chamber ovoidal horizontal cross sections havingmaximum outward dimensions at locations lesser horizontal distances fromsaid casing partition than horizontal midpoint distances of said mixingchambers from said partition.

13. The headphone construction as defined in claim 4 in which similararcuate protrusions are formed principally on said casing partitionprojecting principally from said partition into each of said forward andrearward mixing chambers.

14. The headphone construction as defined in claim 4 in which similararcuate protrusions are formed principally on said casing partitionprojecting into each of said forward and rearward mixing chambersprincipally from said partition, said forward mixing chamber protrusionprojecting principally from said partition generally toward said forwardmixing chamber forward extremity, said rearward mixing chamberprotrusion projecting principally from said partition generally towardsaid rearward mixing chamber rearward extremity, said forward andrearward mixing chamber protrusions in projection principally from saidcasing partition being generally ellipsoidal in both vertical andhorizontal cross section.

15. The headphone construction as defined in claim 4 in which similararcuate protrusions are formed principally on said casing partitionprojecting into each of said forward and rearward mixing chambersprincipally from said partition, said forward mixing chamber protrusionprojecting principally from said partition, generally toward saidforward mixing chamber forward extremity, said rearward mixing chamberprotrusion projecting principally from said partition generally towardsaid rearward mixing chamber rearward extremity; said forward andrearward mixing chamber protrusions covering major portions of walls ofsaid casing partition.

1. In a headphone construction, the combination of: a main generallyhollow casing having a generally central opening at an inner sidepositionable at an ear of a person, said casing enclosing forwardly andrearwardly extending segregated acoustic mixing chambers separated by aportion of said casing and each opening through said casing centralopening; and a sound emitting device in each of said mixing chamberspositioned directing sound into the respective of said mixing chambers,said sound emitting devices in each of said mixing chambers beingprincipally directed toward walls of said respective mixing chambersformed by said portion of said casing separating said mixing chambers.2. The headphone construction as defined in claim 1 in which said casingcentral opening forming an acoustic integrating chamber between saidmixing chambers and said ear inwardly of said portion of said casingseparating said mixing chambers.
 3. The headphone construction asdefined in claim 1 in which each of said mixing chambers in extensionthereof outwardly and forwardly and rearwardly from said casing innerside is generally ovoidal in horizontal cross section and generallyellipsoidal in vertical cross section.
 4. In a headphone construction,the combination of: a main casing having a generally vertical partitionseparating said casing into forward and rearward acoustic mixingchambers, said casing being adapted for positioning with a casing innerside against the head of a person covering an ear and with saidpartition at said ear, said casing and said partition forming wallsdefining said chambers; said forward mixing chamber opening through saidcasing forwardly of said partition to said ear; said rearward mixingchamber opening through said casing rearwardly of said partition to saidear; and a sound emitting device in each of said mixing chambersdirecting sound into the respective one of said mixing chambers, saidsound emitting devices in each of said mixing chambers being principallydirected toward walls of said respective chambers formed by saidpartition.
 5. The headphone construction as defined in claim 4 in whichsaid sound emitting device in said forward mixing chamber is at aforward extremity of said forward mixing chamber directed rearwardly;and in which said sound emitting device in said rearward mixing chamberis at a rearward extremity of said rearward mixing chamber directedforwardly.
 6. The headphone construction as defined in claim 4 in whichsaid forward and rearward mixing chambers communicate through saidcasing inner side through an acoustic integrating chamber in said casinginwardly of an inner termination of said partition.
 7. The headphoneconstruction as defined in claim 4 in which said walls of said forwardand rearward mixing chambers outwardly of said casing inner sideincluding said partition are arcuate in horizontal cross section.
 8. Theheadphone construction as defined in claim 4 in which said walls of saidforward and rearward mixing chambers outwardly of said casing inner sideincluding said partition are arcuate in vertical cross section.
 9. Theheadphone construction as defined in claim 4 in which said walls of saidforward and rearward mixing chambers outwardly of said casing inner sideincluding said partition are arcuate in both vertical and horizontalcross section.
 10. The headphone construction as defined in claim 4 inwhich said walls of said forward and rearward mixing chambers outwardlyof said casing inner side including said partition are generallyellipsoidal in vertical cross section.
 11. The headphone construction asdefined in claim 4 in which said walls of said forward and rearwardmixing chambers outwardly of said casing inner side including saidpartition are generally ovoidal in horizontal cross section.
 12. Theheadphone construction as defined in claim 4 in which said walls of saidforward and rearward Mixing chambers outwardly of said casing inner sideincluding said partition are generally ellipsoidal in vertical crosssection and generally ovoidal in horizontal cross section, said mixingchamber ovoidal horizontal cross sections having maximum outwarddimensions at locations lesser horizontal distances from said casingpartition than horizontal midpoint distances of said mixing chambersfrom said partition.
 13. The headphone construction as defined in claim4 in which similar arcuate protrusions are formed principally on saidcasing partition projecting principally from said partition into each ofsaid forward and rearward mixing chambers.
 14. The headphoneconstruction as defined in claim 4 in which similar arcuate protrusionsare formed principally on said casing partition projecting into each ofsaid forward and rearward mixing chambers principally from saidpartition, said forward mixing chamber protrusion projecting principallyfrom said partition generally toward said forward mixing chamber forwardextremity, said rearward mixing chamber protrusion projectingprincipally from said partition generally toward said rearward mixingchamber rearward extremity, said forward and rearward mixing chamberprotrusions in projection principally from said casing partition beinggenerally ellipsoidal in both vertical and horizontal cross section. 15.The headphone construction as defined in claim 4 in which similararcuate protrusions are formed principally on said casing partitionprojecting into each of said forward and rearward mixing chambersprincipally from said partition, said forward mixing chamber protrusionprojecting principally from said partition, generally toward saidforward mixing chamber forward extremity, said rearward mixing chamberprotrusion projecting principally from said partition generally towardsaid rearward mixing chamber rearward extremity; said forward andrearward mixing chamber protrusions covering major portions of walls ofsaid casing partition.